Cellulosic structures and method of producing same



July 22, 1941. 1 w. H. CHARCHEI'AL CELLULOSIC STRUCTURE AND METHODPRODUCING S AME Filed Dec. 21, 1937 BY M ' ATTORNEY Patented July 22,1941 CELLULOSIC STRUCTURES AND METHOD OF PRODUCING SAME William HaleChar-ch, Buffalo, and William Frederick Underwood, Amherst, N. Y.,assignors to E. I. du Pont de Nemours & Company, Wilmington, Del., acorporation of Delaware Application December 21, 1937, Serial No.180,976

17 Claims.

This invention relates to new artificial fibers, filaments, threads andthe like, and more specifically, to new artificial cellulosic fibers orfilaments which possess an inherent and permanent crimp as one of theirnative properties; to yarns, threads, etc., composed of the same; and tothe process whereby crimp-containing, that is, crimpy' filaments,threads and the like are directly spun in the crimpy condition.

The prior art of spinning artificial threads and filaments has beenbuilt up on methods which directly and inherently produce straightfilaments, in that fine streams of a spinning liquid are forced into acoagulating bath through fine orifices in a spinneret and the formedfilaments are drawn away therefrom in substantially straight andparallel fashion, preparatory to their being wound upby a suitablecollecting device. The finished product of this art has thus been in theforms of yarns, threads or filamentous masses composed of substantiallystraight continuous filaments resembling in many respects the straightcontinuous filaments of natural silk. Alternately it is often requiredto out these continuous artificial filaments into staple lengths forblending with natural staple fibers or to be used alone in staplespinning processes. However, the basic Properties of the originalfilaments including their structure and form are in no wise inherentlyaltered thereby.

The nature of the artificial spinning and setting processes employedheretofore has been such as to limit the practice to th spinning ofsubstantially' straight fibers if one would obtain a product showinggood strength, elasticity, fineness, luster, and other desirableproperties required by the textile trade. In order to achieve asatisfactory product and therewith an economical, smoothly runningspinning operation, it has been the practice to eject the spinningsolution through the small orifices of a spinneret into a bath whichcoagulates the spinning liquid, and to draw away the formed filamentsfrom the spinneret and through the coagulating medium at a wind-up speedin excess of the speed straight line from the instant the spinningliquid passes through the spinneret holes. Frequently special devicesare employed to accentuate or better control this stretch. The extent ofstretch or draw applied varies with different processes, depending uponthe strength,

luster, dyeing characteristics, denier, and other properties desired inthe finished product. The stretch being applied during the interval ofcoagulation of necessity causes the thread throughout the process to besubjected to a certain de gree of tension in the direction of itslength. The tension, whether developed through the tendency of thethread to shrink, or otherwise, will further act to produce the inherentstraight form of the end product. These factors thus combine to producea fiber whose internal molecular structure is such that it is, or tendsto be ipso facto and by nature substantially and permanently straightthereafter, except as new shapes may be mechanically imposed upon it insome later textile operation such as twisting, curling, knitting,weaving, carding, dyeing, drying, finishing, and the like. The commonlyemployed chemical purification treatments, such as washing, desulfuring,bleaching and the like merely serve to' remove foreign impurities andact in no wise to substantially alter or displace the basic molecularstructure and normally straight form which was imposed upon thefilaments in their process of extrusion and hardenmg.

When the internal molecular structure of threads and filaments, spun inaccordance with the previously known methods describedabove, is observedby means of X-ray diffraction patterns, it is noted that the longmolecules of which they are composed lie so as to show a certainpreferential orientation in the direction of the fiber axis. Generallyspeaking, the degree oi orientation observed is the greater according tothe greater stretch and/or tension employed while the filaments werebeing coagulated duning the spinning operation. It is also commonlyobserved that greater strength in the finished yarn accompanies thegreater degrees of molecular orientation. While the extent oforientation may vary, its presence is a common characteristic ofartificially spun fibers as heretofore manufactured. Many naturallyoccurring fibers likewise exhibit preferential molecular orientation inthe direction of the fiber axis, but it is generally held that in thecase of artificially spun filaments, the molecular orientation resultsfrom and is controlled by the stretching and/or tension exerted on themduring the period of their formation in the setting baths.

Thus, the spinning processes for artificial filaments have beenconducted under a set of conditions wherein the size of the spinningorifice, speed of delivery of spinning liquid through the orifices, thegreater speed of draw-off and windup of the coagulated thread, tensionsduring coagulation, bath compositions, temperatures, and many otherfactors are all related and controlled to determine the precisecharacteristics of the final product. While these various factors may bevaried at will within certain limits without adverse effects in thefinished product, radical departures from conventional practice havebeen found to result in threads and filaments of no utility as textileproducts.

If, for example, the conventional process is modified so that one spinswithout due regard to the speed of drawing off of th filaments from thespinneret orifices, and allows the speed of draw-oil to drop to a smallfraction of the speed of extrusion, there is obtained a dull spongyfilamentous mass of little tenacity and great fragility. The filamentscomposing the mass, in addition, will be frequently stuck together andhopelessly entangled. The phenomenon is familiar to those engaged inspinning viscose fibers, in the form of what is known as spinners fiufior "worms." This abnormal material may be observed just prior tothreading up a spinning position at which time the filaments from thenozzle are commonly allowed to issue freely into the bath without beingrapidly carried away. A disorganized mass of weak brittle fibers asdescribed above is obtained. Spinners fluff is total waste and isentirely discarded by manufacturers as having no textile utilitywhatever. Even though these fibers be further processed by carefulwashing, desulfuring, bleaching and drying, the end product is stillvery weak and brittle, being usually so fragile as to easily break up orpulverize when rubbed between the hands.

The formation of this spinners fiufif is an excellent illustration ofthe adverse effects attending a radical departure from commonly acceptedspinning practices. It particularly illustrates the importance which hasbeen attached to the maintenance of a proper ratio of extrusion velocitythrough the spinning orifices to the rate of draw-off of the coagulatedthreads, wherein the latter is made to exceed the former and thus resultin stretch and tension on the thread as it is hardened. It is notsurprising, therefore, that great emphasis has been attached to themaintenance and control of these relationships in the manner described,in order to achieve high quality artificial textile fibers of goodstrength, elasticity, fineness, luster, etc., suitable for the demandsof the textil trade.

The previously known artificial fiber products have thus far found awide range of utility in the field of textiles. However, suitable asthey have proven for many types of fabrics, the fact remains that due tothe compact and dense nature of threads formed from such inherently andsubstantially straight fibers, it has been extremely difficult and inmany cases impossible to use them in the construction of fabrics wheregreat covering power, fill, light weight, warmth, depth, bulk and otherrelated features were desired. These are the properties chieflyassociated with fabrics made from the various natural wool fibers. As aconsequence, numerous attempts have been made to impart to suchartificial threads and filaments a curled, kinky or crimped form inorder to sufficiently change their character in this respect as topermit a wider range of utility. Particularly have attempts been made toimpart to artificial staple fibers a certain curl or waviness in orderto improve the coherence of these fibers in the textile operations,where they are formed into a loose bat or sliver, either alone or mixedwith natural fibers.

In one method the bundle of continuous filaments in the acid setcondition is caused to pile up on itself by the use of a scraper heldagainst the draw-off roller in very much the same manner in which crepeis imparted to certain papers. In other processes the continuousfilaments are cut into staple lengths after being removed from the acidsetting baths, foilowing which the purification operations are conductedon a loose or more or less heterogeneous mass of fibers, therebyallowing them freedom of movement and shrinkage to facilitate theirassuming a wavy shape. The fibers are also dried in the loose condition.frequently after opening of the fiber bundles, thereby to aid theirheterogeneous character. Either alone or combined with other processes,chemical shrinking agents such as acids, alkalies and other solutions,either hot or cold, have been employed on the loose fibers in order toaccentuate their curling. In still other processes, corrugated rollershave been employed at one point or another to impress sinuosities uponthe formed filaments and it has even been suggested that artificialthreads composed of continuous filaments be twisted to a high number ofturns per inch, following which they are steamed and dried and thenreverse twisted so as to produce a yarn composed of curly fibers.

All of the many processes devised for imparting crimp to fibers arecharacterized by the fact that the fibers are originally spun in theconventional manner; that is, as initially straight filaments which areextruded and coagulated with the employment of stretch and/or tension.At some subsequent stage the straight filaments have been submitted to amechanical and/or chemical treatment for the purpose of imparting acurly or wavy character to them. By virtue of this fact, the curlinessis usually temporary, or at best only of a semi-permanent character isregards its crimp regain after wetting, stretching, washing, and similartreatments. Furthermore, the fundamental molecular orientation of thecellulose molecules in the direction of the fiber axis stillcharacterizes these fibers after the curling treatment, since thisproperty is dependent, upon the conditions of tension and/or stretchprevailing between the spinneret and the wind-up device at the time oftheir formation. They are to be regarded as inherently straight fibers,with the internal structure of such fibers, upon which has been laterimpressed a curliness or waviness by some after-treatment which does notbasically affect their internal structure and characteristics. On abasis of rigid tests, it is found that their curliness or waviness doesnot tend to persist as a permanent and inherent property under a widerange of tests, treatments and conditions of use. Furthermore, suchcrimp or curl is not usually, and, in fact for many purposes need not benecessarily, fine or deep, so that as a general rule there is acomparatively small number of undulations per inch.

It has been further proposed to treat fibers, or fiber masses, curledafter the production of the fiber, by means of a synthetic resin and/orformaldehyde, for the purpose of setting said curl or waviness, therebyimparting a greater degree of permanence thereto. The urea-formaldehyde,phenol-formaldehyde and other aldehyde resins have been used for thispurpose and indeed some progress has been made by such methods inimproving the permanence and lasting qualities of the curl. Suchmethods, however, tend to more or less embrittle the fibers, and tointerfere with their normal dyeing properties. The effect on theuniformity of dyeing is such as to make continuous threads treatedbefore weaving or knitting unsuited to most uses. The treatments,therefore, apply primarily to cut staple. That such setting processesare used on curled fibers in order to improve the lasting qualities oftheir curl is evidence of the semi-permanent and transitory character ofthe curl when imparted to cellulosic fibers after their originalformation in the straight condition. While the permanence of said curlis improved. by such resin treatments, it is recognized that this is notdue to any basic structural property of the cellulosic fiber itself, butto the settingeffects of the chemi cal after-treatment in fixing thefiber in its new shape. Indeed the finished product in such cases is nolonger a pure cellulosic fiber, but rather a new material structurecomposed of cellulose and the resin and/or formaldehyde, eitherchemically or mechanically bound into a composite structure.

In view of the prior art of spinning artificial fibers, which art isbuilt on a recognition of the necessity for spinning straight filamentsunder conditions employing stretch and/or tension thereon in the settingprocess, and in view of the known adverseeffects of widely departingfrom such practice, as is illustrated in the formation of spinnersfluff, it is indeed surprising to find that it is possible to directlyspin inherently, permanently, and highly crimpy cellulosic filaments ofgood strength and elasticity and having other desirable properties, bymeans of the process hereinafter described.

Therefore, it is an object of this invention to providev as a newproduct cellulosic filaments and threads possessing an inherent andpermanent crimp, together with good strength and other desirablephysical properties.

It is another object of this invention to produce as a new productcellulosic filaments and threads of good strength possessing an inherentand permanent crimp, which filaments are substantially free frommolecular orientation in the fiber axis and which are substantiallyuncrenulated.

Another object of this invention is to provide very deep, inherently andpermanently crimpy cellulosic filaments and threads with crimps formedand persisting in three dimensions, and with a large number of crimpsper inch, said filaments possessing good strength and other desirablephysical properties.

Still another object of this invention is to provide novel methods ofdirectly spinning crimpy filaments and threads of good strength fromsuitable cellulosic solutions or dispersions.

Still another object of this invention is to provide novel methods offurther processing said crimpy filaments and threads.

Still another object is to provide new and improved coagulating bathssuitable for directly spinning highly crimpy filamentous structures ofgood strength and other physical properties.

Still another object is to provide a process of deepening the crimps inthe filaments after they have been formed.

Other objects will be apparent from the description that follows.

The invention will be more easily understood by reference to thefollowing detailed description and the accompanying illustrations, inwhich, 7

Fig. 1 is a copy of a highly magnified photographic cross-sectional viewof a plurality of crenulated filaments produced by the conventionalstretch-spinning process in which the filaments are spun in an activeregenerating bath.

Fig. 2 is a copy of a highly magnified photographic cross-sectional viewof a plurality of substantially uncrenulated filaments produced inaccordance with the present invention in which the filaments are spun ina fast acting coagulating bath which has a slow or delayed regeneratingaction.

Fig. 3 is a diagrammatic cross-sectional view of a simple form ofapparatus suitable for use in carrying out the process of thisinvention.

The present invention comprises a new cellulosic fiber possessinginherent and permanent crimps in three dimensions, said fiber possessingsubstantially no molecular orientation in the direetion of the fiberaxis, and showing good strength, elasticity, and other desirablephysical properties. This invention further comprises the process ofspinning said inherently crimpy fibers, wherein fine streams of aspinning solution are forced through the orifices of a spinneret into asuitable coagulating medium at a speed several or more times greaterthan the rate at which the coagulated threads are drawn off and removedfrom the coagulating medium, whereby the filaments spontaneously assumetheir finely crimpy form immediately upon issuing from the spinneretorifices into the bath, 'said form persisting as one of their permanentstructural characteristics. The invention further comprises the use ofan initial setting bath with a strong and rapid precipitating,coagulating and/or dehydrating action with substantially no regeneratingaction, or only a slow or delayed regenerating action, in combinationwith a set of spinning conditions wherein the jet velocity of thespinning solution through the orifices is several or more times greaterthan the rate of removal of the formed threads from the coagulatingbath, preferably followed by a treatment to complete the hardening orregeneration of the filaments in the crimpy condition.

Referring to Figure 3 of the drawing, the cellulosic spinning solutionis extruded through the orifices of spinneret l3 into a fast actingcoagulating bath M. The crimpy filaments l5 are passed over guide rollsl6 and i1 and then onto a windup roll I8 which is driven at a speed tomove the thread at a substantially uniform rate of speed. The speed ofthe thread as it is being drawn from the bath of the windup roll 18 isthe draw-off speed of the thread. This draw-off speed of the thread ismaintained much lower than the jet velocity of the spinning solutionissuing from the orifices so that the filamentous solution as it flowsfrom the spinneret buckles and bends as it is forced into the bath.

The threads or filaments thus produced are thereafter washed.desulfured, bleached, or otherwise purified by known methods. Prior tothe final drying of the threads or filaments. they are given a treatmentwith a finishing solution such as may be composed of oils, soaps,sulfonated oils, and the like. After freeing the threads or filamentsfrom excess adhering solution, they are dried in a free, loosecondition, for instance in the form of skeins, and preferably with theemployment of some agitation during the drying process. Such agitationmay be supplied by currents of moving air or by suitably actingmechanical devices, or both, or by other well known agitating means.

Quite surprisingly it has been found that a depending and accentuationof the crimps of the fiber can be obtained by submitting the formedcrimpy threads or fibers to a stretching treatment in the wet state andthereafter relaxing the stretched thread, said treatment being appliedat any time following completion of the regenerating step. The amount ofstretch employed may vary from a few per cent up to as much as 40 or 50per cent, or in some cases even more. Indeed, it has been found possibleto stretch the threads or filaments to just short of their breakingpoint, thereafter completely relaxing the thread, further processing,and finally drying it still in the relaxed condition to obtain filamentswith greater depth of crimp. The amount of stretch, which is herereferred to, and which is employed, is in addition to that required tojust straighten out the original crimps in the filaments. The amount ofrelaxation after stretching is sufiicient to completely relax thethreads and it is allowed to take place, before further processing anddrying. While it might be supposed that such drastic stretching wouldresult in completely and permanently destroying the crimpy properties ofthe fibers, it is found on the contrary, that the general character andthe permanence of the crimp is not adversely affected thereby, butindeed upon drying the yarn relaxed and with external agitation, itresults that the depth of the crimps is usually somewhat improved overwhat it would have been in the absence of such stretching treatment.While this stretching treatment is optional, in the preferred form ofprocess the yarn will usually be subjected, at some stage fol lowingcompleted regeneration, to a certain stretch, as by nipping it betweensets of rollers rotating at different speeds or by other suitabledevices, or by devices which stretch an entire skein, and the like. Thestretching is preferably carried out on yarn or filaments which arethoroughly wet with water or water containing finishing materials, andat room temperature. If room temperature or slightly chilled water isemployed, a greater degree of'stretch may usually be imparted-than canbe achieved by the use of hot water. If the stretching is carried outjust prior to the final drying of the yarn, it may be convenient to wetor rewet the yarn with water containing a small amount of finishingagents, such as soaps, sulfonated oils, emulsions of oils, lubricantsand other finishing agents commonly employed on artificial fibers. Inother instances the stretch may be applied during the washing orpurification steps which follow coagulation and regeneration. In thiscase, the threads are processed singly and continuously on suitablemachines for the purpose. The fact that the threads or fibers can besubmitted to such severe stretching as above described and will not onlystill regain their original crimp, but may be frequently improvedthereby, is remarkable evidence of the inherent and permanent characterof their crimp which distinguishes them from crimped or curled fibersheretofore produced.

Throughout this specification the jet velocitydraw-off ratio isfrequently referred to. This expression is used for convenience andrefers to the ratio of the velocity of spinning fluid through thespinneret orifices to the speed at which the coagulated and formedthreads or filaments are drawn through the coagulating bath and awayfrom the spinneret.

The several specific examples that follow will serve to illustrate thedetails of the invention, but it is to be understood that these examplesare in no way limitative of the invention.

Example 1 Viscose containing 7% cellulose and 6% sodium hydroxide,ripened to a salt index of 4.2, was extruded at the rate of 8.50 gramsper minute through a spinneret having 40 holes, each hole being .004" indiameter, into an aqueous coagulating bath containing 44.3% ammoniumsulfate and 0.3% ammonium hydroxide at a temperature of 45 (2., wherebythe filaments composing the thread were coagulated and spontaneouslyassumed a crimpy form at once upon issuing from the spinneret. Thethread was drawn 20 inches through the bath, and wound onto a bobbin ata speed of 227" per minute. Since the jet velocity was equal to 930" perminute, the ratio of jet velocity to draw-oil was about 4.1.

The thread was thereafter regenerated by immersing the bobbin of yarn inan aqueous bath containing 20% sulfuric acid, 18% sodium sulfate and 10%glucose at 25 C. The yarn still on the bobbin was washed with soft waterto free it from acid, desulfured in a hot dilute sodium carbonatesolution, and finally washed free from alkalinity with soft water. Thewet yarn was given two turns per inch of twist on a ring twistingmachine, following which it was reeled into skeins while still wet. Theskeins were then immersed in a hot aqueous finishing solution containinga sulfonated oil, freed from excess solution by centrifuging wringing,and then dried in a relaxed condition while agitating the skeins bymeans of moving air and mechanical movement of the skein itself.

The resulting yarn was substantially uncrenulated, was substantiallyfree from molecular orientation along the fiber axis, and possessed athree-dimensional crimp which was retained upon repeated wetting anddrying of the yarn and under conditions of use.

Example 2 Viscose such as described in Example 1 was extruded at therate of 28.69 grams per minute through a spinneret containing holes,each hole being .0015" in diameter, into a bath having the samecomposition and at the same temperature as was used in Example 1, andafter 20" of travel in the bath the crimpy yarn formed was wound up at aspeed of 598" per minute. The nozzle velocity was 8900" per minute,giving, therefore, a ratio of jet velocity to draw-01f speed of about14.9. This yarn was regenerated, purified, dried, and otherwise finishedin the manner described in Example 1.

Example 3 Viscose such as described in Example 1 was extruded through anozzle containing 40 holes, each hole being .002" in diameter, at therate of 4.7 grams per minute, into a bath of the same composition and atthe same temperature as used in the above examples and after passing 20"through this bath the crimpy yarn thus produced was wound up at 372" perminute. This represents a nozzle velocity of 2055" per minute, and,therefore, a ratio of nozzle velocity to draw-ofl speed of about 5.5.After regenerating, desulfuring, and twisting, as described underExample 1, the wet yarn was stretched 50% over and above that stretchnecessary to just straighten out the crimp, and then wound onto a bobbinin a relaxed condition, following which it was reeled into skeins andwas then finished and dried in the manner described in Example 1.

The yarn so produced was woven on a commercial loom using 36/2 spunrayon as a warp, warp spacing 74 ends per inch, and a 2/2 serge weavewith a filling of the above yarn, using 53 picks per inch. This clothwas given commercial dyeing and finishing treatments. The resultantcloth due to thecrimp in the filling yarn, possessed an appearance andhand similar to that of a worsted fabric. When the cloth is viewed undera five power hand magnifying glass the improved filling power of thecrimpy yarn is readily noted.

Example 4 Cotton linters viscose containing 7% cellulose and 6% sodiumhydroxide, having a salt index of 0.5 was extruded through a spinnerethaving 100 holes, each hole being .002" in diameter, at the rate of20.85 grams per minute, into a coagulating bath containing 43.89% sodiumsulfate and 0.13% ammonium hydroxide at 45 C. The crimpy yarn thusformed after passing 20" through the bath was wound up at a draw-offspeed of 474" per minute. After the spinning cake was completed, theyarn on the bobbin was Example Cotton linters viscose containing 7%cellulose and 6% NaOH, having a salt index of 4.0 to 4.2, was extrudedat the rate of 20.06 grams per minute, through a spinneret containing100 holes, each hole being .002" in diameter, into a bath containingapproximately 45% ammonium sulfate and 0.3% ammonium hydroxide at 45 C.,and the erimpy yarn thus formed after 20" bath travel was wound up on abobbin at the rate of 385" per minute. The nozzle velocity was 3520" perminute, which meansthat the ratio of jet velocity to draw-off speed wasabout 9.1. The coagulated yarn was regenerated on the bobbin, was washedand purified as in Example 1. The wet yarn was given 2.75 turns per inchof twist on a ring twister and then while still wet was stretched 50%,wound into skeins, finished, and finally dried in a relaxed and agitatedcondition, asdescribed in Example 1. This yarn was woven on a commercialloom, using a 6/1 warp thread made up of 85% 5.5 denier per filamentdull spun rayon and 64 wool with 26 .ends per inch and with the yarn ofthis example as the filling thread at the rate of 15 picks per inch, toform a plain weave fabric. The resultant fabric was given the samecommercial finishing treatment as that used for the fabric describedunder Example 3. This fabric, due to the great covering power of thebulky and lofty crimpy filling yarn, when compared with a fabric of thesame construction but made with a filling yarn similar to that of thewarp threads, and finished in exactly the same manner, showedconsiderably more body.

Example 6 Cotton linters viscose containing 7% cellulose, 6% sodiumhydroxide, having 'a salt index of 4.0, was extruded at the rate of20.75 grams per minute, through a spinneret containing holes, each holebeing .002 in diameter, into a coagulating bath of glacial acetic acidat room temperature and after passing the crimpy yarn formed 20" throughthe bath, it was wound up on a bobbin at 340" per minute. The resultingyarn was regenerated slowly as spun, and, therefore, required nosubsequent regenerating treatment. The yarn was washed, desulfured, andtwisted to two turns per inch, as previously described, and then withoutdrying was stretched 50%, reeled into skeins, finished, and finallydried in a relaxed condition as described in Example 1. The yarn soproduced possessed an excellent three-dimensional crimp, a semi-dull orsilk-like luster, andwas quite soft.

Example 7 The viscose as described under Example 6 was spun in the samemanner as in Example 6, except that an aqueous coagulating bathcontaining 40.5% ammonium sulfate and 1.12% acetic acid was used at 45C. The viscose delivery was 20.23 grams per minute and the windup speedwas 474 per minute. The crimpy yarn produced was not regenerated by thisspinning bath but was regenerated on the bobbin by a bath consisting of20% sulfuric acid, 18% sodium sulfate, and 10% glucose at 25 C. Afterwashing, desulfuring, and twisting to two turns per inch in the mannerdescribed in Example 1, the yarn was wet stretched 40%, was reeled intoskeins, finished, and then dried in a relaxed condition as described inExample 1.

Example 8 This example was carried out in the same manner as Example 7,except that the coagulating bath contained 40.5% ammonium sulfate, 0.93%sulfuric acid at 45 C., and the windup speed was 438" per minute.Although the crimpy yarn produced was slowly regenerated by thisspinningbath, it was afterward immersed in 20% sulfuric acid, 10%glucose, and 18% sodium sulfate bath at 25 C. to hasten regeneration.The yarn was further treated and finished in the manner as described inExample 7.

Example 9 Viscose containing 7% cellulose and 6% sodium hydroxide,ripened to a salt index of 4.2 was extruded at the rate of 20.7 gramsper minute through a spinneret having 100 holes, each hole being .002"in diameter, into an aqueous coagulating bath containing 5.75% sulfuricacid and saturated with ammonium sulfate at 45 C. The filamentscomposing the thread assumed a crimpy form at once upon issuing from thespinneret. The thread was drawn 20 inches through the bath and woundonto a bobbin at a speed of 438 per minute. This represents a nozzlevelocity of approximately 3620" per minute. Therefore, the ratio ofnozzle velocity to draw-off speed Was about 8.27. The yarn wasregenerated as wound up on the bobbin, but in order to assure completionof the regeneration the bobbin was immersed in an aqueous bathcontaining 20% cose at 25 C. The yarn still on the bobbin was washedwith soft water to free it from acid, desulfured in a hot dilute sodiumcarbonate solution, and finally washed free from alkalinity in softwater. The yarn, while still wet, was given 2 turns per inch on a ringtwister, following which it was wet reeled into skeins. The skeins werethen immersed in a hot aqueous solution containing sulfonated oil, freedfrom excess solution by centrifugal wringing, and then dried in arelaxed condition while agitating the skeins by means of moving air andmechanical movement of the skein itself. The resultant yarn wassubstantially uncrenulated, substantially free from molecularorientation along the fiber axis, and possessed a three-dimensionalcrimp which was retained upon repeated washing and drying of the yarnand under conditions of use.

Example 10 A methyl cellulose containing /2 mol of methyl for each sixcarbon atoms of the cellulose molecule was dissolved in 7% sodiumhydroxide solution at C. to yield a 7% methyl cellulose solution. Thissolution was extruded at the rate of 20.7 grams per minute through aspinneret containing 100 holes, each hole being 0.002" in diameter, intoan aqueous coagulating bath containing approximately 45% ammoniumsulfate, 0.3% ammonium hydroxide and 10% glucose at 45 C. and the crimpyyarn thus formed was wound up on a bobbin at 340" per minute. The jetvelocity was about 3620 inches per minute, resulting in a ratio of jetvelocity to draw-off speed of about 10.6. The coagulated yarn whilestill on the bobbin was then immersed in sulfuric acid, 18% sodiumsulfate, and 10% glucose bath at C. for 10 minutes, and then washed,purified, twisted, skeined, finished, and dried as described in Example1.

Example 11 A viscose solution containing 7% cellulose, 6% sodiumhydroxide, ripened to a salt index of 4.0, was spun into a saturatedsolution of sodium sulfate at 45 C., using a spinneret containing 100holes, each hole being 0.002" in diameter, and a viscose delivery rateof 20.75 grams per minute. The crimpy yarn was passed through 20 inchesof bath and wound up on a bobbin at 313" per'minute. The jet velocitywas about 3630" per minute, which gave a ratio of jet velocity todraw-off speed of 11.6. The resultant.

yarn was regenerated, purified, twisted, skeined, finished, and dried inthe manner described in Example 1.

Example 12 Viscose containing 4% cellulose and 3.45% sodium hydroxidewas extruded at the rate of 4.81 grams per minute through a spinneretcontaining holes, each hole being .002" in diameter, and after passingabout 20" through a. ammonium sulfate bath at 45 C., the crimpycoagulated cellulose xanthate yarn was wound up on a bobbin at the rateof 238" per minute. The jet velocity was 2103" per minute, whichresulted in a ratio of jet velocity to draw-off of about 8.8. The yarnwas regenerated and otherwise treated in the manner described underExample 4.

Example 13 Viscose was prepared in the usual manner from wood pulp toproduce a solution containing 8.5% cellulose and 6.5% NaOH and afterripening to a salt index of 1.9 was extruded at the rate of 20.35 gramsper minute through a hole spinneret, each hole being 0.002" in diameter,into the same coagulating bath described in Example 12 to produce crimpyyarn and after passing 20 inches through the bath the yarn was wound upon a bobbin at 535" per minute. The nozzle velocity was 3560 per minute,resulting in a ratio of jet velocity to draw-off of about 6.6. The yarnwas regenerated and otherwise threaded in the manner described underExample 4.

For convenience the invention has been largely described in itsapplication to the production of regenerated cellulose fibers andfilaments as produced by the viscose process. It is to be understood,however, that it is not limited thereby, but the principles of theinvention may be applied to the spinning of cuprammonium cellulosethreads and filaments and other cellulosic threads and filaments byother processes. An example for the spinning of methyl cellulosefilaments has been given. In similar and appropriate manner one may, inaccordance with the present invention, spin crimpy filaments from othercoagulable aqueous cellulosic filament-forming solutions or dispersions.

In applying this invention to the spinning of crimpy filaments fromviscose use may be made of any viscose suitable for the spinning of theusual prior art threads or fibers, or any especially prepared viscosecoagulable in aqueous or non-aqueous setting baths. ,In practice,particularly desirable results are obtained by use of a viscose preparedin the usual manner and ripened to a salt index of from 2 to 4%,determined as described on page 68, paragraph 2 of "Artificial Silk" byReinthaler and Rowe, published in 1928. To regulate special effects,however, such as softness and harshness, or luster or dullness, viscosewith an index as high as 9, and as low as 0.5 has been spun with theproduction of good crimpy filaments. It is also possible to use aviscose modified by the addition of well known modifying agents such asdelustering agents, including pigments, as well as liquid and organicdelusterants. It is furthermore possible to employ viscose modified bythe addition of materials which aifect or influence any one of the manydyeing properties of the spun fibers. Where fiber dyeing is desiredhaving a susceptibility to acid dyes such as are commonly employed inthe dyeing of wool, various dye modifiers, such as are commonly employedfor this purpose may be added to the viscose. Viscose may be otherwisefurther modified for still other purposes and when spun by means of theinvention will produce inherently, permanently, and highly crimpythreads or filaments.

As previously pointed out, a high ratio of jet velocity to draw-offspeed is essential to and a part of the invention. The jet velocity isseveral or more times greater than the draw-off speed of the filaments.For spinning very crimpy filaments, the jet velocity-draw-ofi ratio ispreferably and approximately at least four when employing the usualtypes of viscose and setting baths, as described herein. The jetvelocitydraw-oif ratio may be as high as 5, 8, 10, 12, 20 or evenhigher, depending upon the special effects desired in the finished yamand/or the special properties of the viscose and/or coagulating bathsemployed. It will also depend upon the diameter of the extrusionorifices in the spinneret, as well as upon the diameter of the filamentsto be spun. For instance, in the spinning Another reason forrequiringbath of powerful coagulating properties is to avoid stuckfilaments. Baths which coagulate slowly do not set up the crimpyfilaments sufiiciently to prevent them from sticking to each other afterextrusion.

The usual range of bath temperatures may be employed or the temperatureof the bath may be substantially increased or lowered without departingfromthe invention. Temperatures between 40 and 50 C. are commonly used.

The formation of crimpy filaments spun in the manner described abovetakes place immediately, or almost immediately following the issuance ofthe streams of spinning solution from the spinneret orifices. Usuallythe formation of these crimps will have been completed within the firstinch or less of bath travel, subsequent travel being used largely tocomplete hardening and setting and/or to initiate the regeneration stepas when the bath may be weakly acidic, as above described. In causingthe fine streams of spinningsolution to curl and buckle back uponthemselves directly upon issuing from the spinning orifices, meanwhileacting on them by means of a rapidly coagulating bath, a crimp which isbased, so to speak, upon the molecular structure of the fiber itself isobtained. By carrying out regeneration of the filaments in theiroriginal crimpy .shape, the internal molecular structure of thefilaments has been further and finally fixed so that their natural formis crimpy, as distinguished from prior art fibers whose natural form hasbeen straight.

When employing an initial setting bath of substantially no regeneratingaction, or in some cases when employing an initial setting bath of slowordelayed regenerating action, the coagulated threads are introducedinto a regenerating bath of pronounced acidic properties. For this stepthe stronger mineral acids are preferred; for example, sulfuric acid inconcentrations, for instance, between about 10 and 20%, or higher.

As a rule, it is preferred to use an acid bath containing substantialquantities of some salt such as sodium sulfate or other materials ofcoagulating eflfects such as glucose. A bath containing approximately20% sulfuric acid, 18%

sodium sulfate, and 10% glucose at room temperature serves very well toregenerate the filaments and to yield softness in the final product. Inmany cases acid baths containing higher concentrations of salt maybeused to good advantage and where greater softness is desired. As a rule,baths at or near room temperature appear to give somewhat softer yarnthan very high temperature baths, although one may operate as high as 40or 50 0., if desired. One may, of course, regenerate by other suitablemeans, as by the employment of heat, or by the employment of acidicgases or vapors, such as sulfur dioxide, or by combinations thereof, aswell as by other means. When employing an initial setting bath composedof, or containing substantial amounts of an organic acid coagu lant suchas acetic acid, or when spinning into an initial bath of very slow ordelayed regenerating action, one may, if desired, omit the separateregenerating step, provided that due recognition is given to the use ofconditions which permit completion of regeneration of the cellulosexanthate filaments, as by giving the filaments a sufliciently long timein the bath, the use of higher bath temperatures, etc.

After regeneration, the yarn is washed in any convenient manner, as, forinstance, by immersion, showering, methods. It is desulfured by means ofany of the usual desulfuring agents such as a dilute solution of sodiumcarbonate, sodium sulfide, or the like. The yarn desulfurs very easilyto a good color and for many uses may require no bleaching, but it maybe bleached if desired.

The purified yarn may then be twisted to 2 or 3, or any desired numberof turns per inch, either prior to or after drying. In twisting wetyarn, use is preferably made of a ring twister, or to twist by means offeeding the yarn into acentrifugal spinning bucket. lulose yarn istwisted andcollected in a centrifugal bucket as a cake, furtherprocessing of the yarn may be carried out in that form, if desired. Theyarn can, of course, be first dried and thereafter twisted on suitablemachinery.

In the drying of the-threads or fibers, due precautionsshould beexercised to preserve their crimpy form and to facilitate thedevelopment of a still further depth of crimp during the drying process.The fibers of the invention not only preserve their crimp on drying,but, indeed, during drying assume an even more highly crimpy form.Therefore; the drying is conducted in such a manner as not only not tointerfere with the development of such crimp, but to facilitate itsfurther formation. It is naturally desired to obtain a finished driedproduct of great bulk and flufiiness.

It is, therefore, preferred to apply a finishing or lubricating materialto the yarn prior to its being dried. Such finishes are composed ofsoaps,

oils, emulsified oils and fats, sulfonated oils, mineral oils, and otheragents well known in the art of finishing textiles. It is preferred touse a finish which will permit maximum lubrication and slipping of thethreads and filaments over each other during the drying process. Thefinishes are applied in such amounts as to add from a fraction toseveral or more percent of materials to the yarn based on a dry weightbasis. The yarn, after finishing, may be dried in the form of skeinsinto which form it is reeled while still in the wet condition. Sinceconsiderable contraction of the threads takes place ,due to furthercrimp formation during drying, it is necessary to reel initially arather large diameter skein so as to compensate for its contractionduring the drying process. It is preferable to dry the product whetherin skeins or other forms, by means of moving air, which furnishescontinuous or frequent agitation of the threads and filaments thereof.It is furthermore preferable to employ mechanical devices which agitate,turn, or otherwise cause continuous or frequent movement of the yarn,thus facilitating freedom of movement of the individual threads andfilamentsover and past eachother in their contraction during the dryingprocesses. In drying the skeins may contract to as much as 25 to 50%, ormore of their original wet length, due to further crimp formation. It ispreferred to dry at a relatively slow rate and while one may employhighly heated air, it is usually preferable to conduct the drying at amuch slower rate, as by'means of air at room temperature, or onlyslightly heated, combining therewith suitable agitation, movement, orworking of the skein. Alternately, the product may be dried incontinuous form, as by passing the individual threads through anysuitable drying chamber. Agltation of the threads by mechanical meansand/or moving air is employed to allow contraction of the threads duringor by centrifugal or pressure If the regenerated celof very heavy deniercrimpy filaments measuring as much as 20 or .30 denier per filament, thejet velocity-draw-oif ratio may be as low as four, while for thespinning of much finer filaments such as filaments of or 6 denier orless, it has been found desirable to use a very much higher jetvelocity-draw-off ratio, frequently as much as fifteen, twenty, or evenmore. In general, the jet velocity-draw-off ratio for most yarns will bebetween four and twenty.

The character of the initial coagulating or setting bath in which crimpyfilaments of good strength are formed by spinning with a high jetvelocity-draw-off ratio is a further necessary part of the invention. Afast-acting coagulating bath with no regenerating action, or,alternatively, one with a delayed or slow regenerating action isemployed. Such a bath may be defined as one with very strongdehydrating, salting out, or precipitating action, such as to cause thestreams of viscose issuing from the spinning orifices to be completelycoagulated throughout, or substantially so, before any substantialregeneration is initiated. By thus separating the steps of coagulationand regeneration in the spinning of filaments by the use of a high jetvelocity-draW-off ratio, we obtain permanently crimpy filaments of goodstrength which possess a substantially smooth uncrenulated surface, andshow substantially no molecular orientation in the direction of thefiber axis.

The above may, for example, be accomplished by the use of a bathcomprising a high concentration of a highly soluble salt or a highconcentration of a weak acid containing such a small amount of water asto give a strong dehydrating or precipitating action. An aqueous,saturated or nearly saturated ammonium sulfate bath at approximately 45C. is an excellent coagulating medium. Other highly soluble ammoniumsalts may likewise be used in high concentrations; for instance,ammonium chloride, ammonium carbonate, ammonium phosphate, and the likeas well as other active coagulating salt solutions such as a saturatedsodium sulfate solution. Such baths may be used either with or withoutthe addition of other salts.

For commercial practice, an ammonium sulfate bath of high concentrationat or near saturation is preferred. It is usually preferred to maintainthis bath at or near neutrality. Under these conditions threads composedof a large number of highly crimpy filaments can be spun, whichfilaments show no tendency to stick together. When a somewhat lowerpercentage of salt is employed in the bath, it may be necessary to use alarge faced spinneret in which the holes are spaced wider apart so as topermit free access of the setting bath to the immediate vicinity of thespinneret holes, thereby suppressing the tendency of filaments to sticktogether.

Alternatively, the initial coagulating bath may be operated with severalor more percent active mineral acid, such as sulfuric, providing thatthe bath contains a sufficiently high concentration of salt, or othermaterial, of active coagulating properties as to cause substantiallycomplete coagulation of the spinning fluid before the initiation of anysubstantial amount of regeneration. With such a bath, the acidconcentration may be of the order of several percent or more of mineralacid. Under certain conditions it has been found possible to spin crimpyfilaments of good strength into baths containing as much as 5%, or even7%, sulfuric acid while maintaining an ammonium sulfate concentration ator near the saturation point. When, for example, use is made of astrongly precipitating salt bath of high concentration and containingseveral or more percent mineral acid, the activity of the acid asregards its regenerating properties is diminished. as a result of thehigh salt content. Furthermore, the coagulating, precipitating, orsalting out action of the bath is enhanced as a result of the high saltcontent. Active regenerating acid baths such as have been used in theordinary spinning of straight filament rayon cannot be used in thisprocess since in combination with high jet velocity-draw-off ratio theyhave adverse effccts on the strength, elasticity, and other propertiesof the fibers, and no claim is made for this type of bath as the initialsetting bath for the spinning of crimpy filaments.

Alternatively, as other baths suitable for this process, it has alsobeen found useful to employ organic acids, either alone or containingsome minor percentage of water with or without the addition of salts andthe like. Organic acids such as acetic, formic, citric and the like maybe employed as the initial bath. Glacial acetic acid containing smallamounts of water, possesses marked coagulation properties for thespinning of the crimpy filaments and it is sufiiciently slow in itsregenerating action as to produce strong, soft crimpy yarns of goodproperties. With such a bath it may be unnecessary to submit the formedfilaments to a second and stronger acid bath to complete regeneration,although this can be done if desired.

It is, therefore, apparent that considerable variation in constituents,ranges of constituents, temperatures, and other factors can be made inthe baths to be used for the coagulation of the filaments of the presentinvention. The coagulation and regeneration of the filaments are keptmore or less separated from each other in point of time so thatcoagulation throughout the fiber precedes any substantial regeneration.Baths which operate in this manner produce filaments which aresubstantially smooth and non-crenulated, as opposed to the highlycrenulated filaments produced by baths customarily used for spinningstraight filament viscose rayon and wherein regeneration of thefilaments takes place before the filaments have been coagulatedthroughout.

Referring to Figures 1 and 2 of the accompanying drawing referencenumeral ll designates the highly crenulated straight filaments of theprior art. Numeral l2 designates the substantially non-crenulatedfilaments of the present invention. The cross-sections of the filamentsin both views are drawn from actual magnified photographs of thecorresponding filaments. The crenulations of the prior art filaments arebrought about by the fact that the outer shell of the filament hasbecome regenerated before the inher fluid core has become coagulated.Thus, by the time coagulation of the interior of the filament has beencompleted there occurs a collapse of the filament with the result thatthe outer, already regenerated skin shrinks and shrivels to form afilament with a highly crenulated surface. On the other hand, the rapidcoagulating-slow regenerating baths of the present invention causecomplete coagulation throughout the filament before any substantialregeneration takes place and as a result no outer collapsible skin isformed, but the structure tends to maintain the circular outline whichit had when originally coagulated.

drying. A skein of the yarn thus processed, will possess from 2 to 5, oreven more, times the bulk of prior art straight filament yarns.

While the above description of the process relates to the production ofa continuous filament yarn composed of permanently crimpy filaments, thecontinuous filaments may, if desired, be cut into staple of any desiredlength, either in the wet or dry state, or at any convenient stage intheir processing. It is to be understood for the purpose of thespecification and claims that the terms filaments, fibers," threads, andthe like are intended to cover the product and proc-' ess for the same,as relating to both continuous lengths and short staple lengths.

The filaments, fibers, threads, yarns, etc., of the invention aredistinguished from other artificial fibers in many important respects.Their outstanding characteristic is an inherent and permanent crinkle orcrimp which is regained after wetting and drying, and other treatments,even though the filaments or yarns thereof may become stretched so as totemporarily remove their'crinkle, as hereinafter described. The fibersof the present invention possess a relatively large number of small andvery pronounced un dulations which, ofcourse, will vary in size andspacing according 'to the specific method of spinning, but willgenerally amount to from or less to 50, or more crimps per inch. It ischaracteristic of the fibers that their crimp lies naturally in threedimensions rather than a single plane or nearly so, as is the case withstraight filament yarn upon which crimp has been superimposed by 'meansof gears and similar devices. Furthermore, as a result of the particularmethod of spinning, the crimps in the various filaments issuing from anorifice are formed and quency roughly approximating that of thefrequency of the crimp in the fibers.

The filaments or fibers are further distinguished as a whole by asubstantially smooth, non-crenulated surface and the shape of theircross-section is on the average usually nearly round, or not greatlydistorted from a round remain out of phase with each other. This isadvantageous in yielding threads or yarns of great bulk, loft, coveringpower and resiliency, similar in many respects to woolen yarns. A moredetailed description of the permanent nature of the crimp of thefibersis given later herein. i

The filaments or fibers of the present invention are furtherdistinguished by observing their X- ray diffraction patterns, whichdemonstrate that their molecular structure shows no preferentialorientation of the molecules or micelles in the direction of the fiberaxis. While the fibers show a crystalline structure common to allregenerated cellulose fibers, there is an absence of orientationeffects. The fibers are further distinguished by their appearance inpolarized light, when viewed through a polarizing microscope. Viewed inthis manner, they show distinct, frequent, and abrupt alternatingcolored and uncolored patches, more or less regularly disposed in thelong direction of the fiber. Prior art filaments and fibers which havebeen spun and set in a straight condition with stretching and/or tensionduring the spinning process, whether or not they have been subsequentlycrimped, show color effects throughout their entire length, and whilethese colors may change or gradually blend one into the other, orsometimes even gradually fade out and then reappear over a comparativelylong fiber length, in no case has a frequent and sharp alternation beenobserved between colored and completely uncolored patches such as may beobserved in the fibers of the present invention. The rapidly alternatingcolored and uncolored patches characterizing the fiber occur with afreshape. In some instances, very fine crenulations are observed on thesurface. These are, however, extremely fine when they occur and do notsubstantially approach the appearance of prior art straight filamentviscose fibers which are deeply and highly corrugated. In the preferredforms of the invention, the fibers are substantially round and possess asubstantially smooth surface.

The filaments or fibers are further characterized by a subdued luster ormatt appearance, which is obtained without the addition of any foreigndelustering agents such as pigments, oils, and the like, heretoforeemployed for the purpose of delustering straight filament rayon. Suchforeign delustering materials may, of course, if desired, be added tothe .viscose prior to spinning in order to achieve still greater orspecial low luster effects, but for many purposes for which the fiber isused, this will be unnecessary, since a fiber with a subdued luster isobtained directly as a result of the method of spinning as hereinaboveset forth. By suitable changes in the degree of ripeness, of the viscoseand/or in the coagulating bath composition and/or the jetvelocity-draw-ofi ratio, the luster effects in the final product may bevaried through a wide range.

The filaments or fibers are further distinguished in their great abilityto absorb dyes as compared to prior art straight filaments spun withstretch and/or tension. When compared to such prior art cellulosicfilaments, the product dyes many shades deeper and much more rapidly,such comparisons being made under comparable dyeing conditions. This isan advantage in commercial processing due to the rigid economic factorswhich prevail in the dyeing and finishing industry.

The filaments, or yarns composed thereof, notably possess good strength,elasticity, and softness, the latter being more apparent in the finerfilament deniers. In the medium or somee what higher deniers, the yarnspossess a very desirable property which may be termed crispness ofhand." This crispness has been found to be advantageous and to carryover and appear in the finished cloth. A twill or other woven fabric,for instance, possesses distinctly more body than when. constructed fromprior art continuous straight filament threads or spun staple threads ofcorresponding denier. The dry strength of the fibers produced in themanner herein described will range from about 0.5 G. P. D. up to 1.25 G.P. D., or in special cases even somewhat higher. As is usualin the caseof regenerated cellulose filaments, the wet strength is roughly half ofthe dry strength. The filaments, or threads composed thereof, however,show an unusually high elongation, both wet and dry, as compared toprior art straight cellulosic filaments spun with stretch and/ortension. The dry elongation of the filaments will be between 35 and 45%and the wet elongation in the neighborhood of twice that figure.Frequently these figures are exceeded, depending upon the method ofpreparation. While the strength of the fibers is somewhat lower thanthat of usual tension spun straight artificial filaments, it issufilcient for the uses to which the product is applied, and, indeed, isvery favorably comparable to, or better than the strength of comparablewool fibers and yarns. The product may be produced in a wide variety ofdeniers per filament, ranging from very small filaments of 3 or 4deniers per filament, or less, up to 20, 30, or even more deniers perfilament. As is usual in the case of natural, as well as artificialfibers, the softer yarns accompany the finer filament deniers and theharsher and stiffer products the higher filament deniers.

A further description of the nature of the crimp possessed by the fibersand the conditions under which it persists will serve to illustrate itsinherent and permanent character. The most simple, direct testillustrating the character of the fibers consists in taking preferably asingle dry finished filament several inches long and thoroughly wettingit with water or by carefully drawing it several times between themoistened lips so as to wet it out. While wet, the filament may be givena substantial amount of stretch over and above that required tostraighten out the crimp. If the experiment is performed by repeatedlydrawing the filament between the moistened lips to wet it, a slightpressure of the lips while drawing the filament through will straightenout the crimp and serve to impart additional stretch thereto.Immediately after wetting has been completed the fiber is held up at oneend (the other end being free) and viewed as it dries, preferablyagainst a. black background in good light. The drying will beaccomplished at room temperature in a minute or so. As the fiber driesit will be noted that it begins to twist, curl, and shorten in lengthand to take on a very decidedly crimpy and sometimes a spiral crimpycharacter, so that by the time its drying is completed it has greatlycontracted from its original wet length and is now curled and irregularand its general form corresponds to that which it possessed immediatelyafter being spun and coagulated. The same fiber may be again similarlywetted and dried, or wetted, stretched and dried, and this may be stillfurther repeated on the same fiber with spontaneous contraction andcrimping occurring. Whether the fiber in this experiment assumes a verylarge or lesser number of crimps per inch will depend primarily on.whether the yarn was initially coagulated to give a large or smallnumber of crimps per inch.

To still further illustrate the inherent, permanent crimpy character ofthe fibers, one way take a single fiber or a small bundle thereof,thoroughly wet it in water, and thereafter stretch the wet filaments atleast 10% or, if desired, even much more. The stretching mentioned hererefers to a stretch over and above that required to just remove thecrimps from the filaments. While still in this set stretched andstraightened condition, and while under tenson, the filaments are thuscompletely dried, without permitting them to contract. The filaments arethen removed from the device which has held them straight during drying.At this stage they are, of course, substantially straight. They are thenthoroughly wet out with water and, after removal from the water, areheld at one end and allowed to dry freely in the air again. In spite ofthe fact that the filaments had been wet stretched and dried in astraightened and stretched condition, they will still again assume theircrimpy shape when allowed to dry freely. Thus, while the filaments orthreads may have been dried to a straightened shape at some stage intheir processing, or in their conditions of use, their crimpy form caneasily be restored by merely rewetting with water, followed by dryingconditions which permit them freedom to contract, and so assume theirnatural crimpy shape. The process described above may be furtherrepeated without destroying the inherent and permanent character of thecrimp.

By way of example, which in no way limits the scope of the invention, atable is appended herewith illustrating the crimp recoverycharacteristics of one typical fiber product after it has been wet inwater and stretched to varying amounts over and above that necessary toremove the crimp, followed by free drying whereby the yarn and/orfilaments are free to contract to their fullest extent. Ten centimeterlengths of approximately 300 denier 40 filament crimpy thread wereimmersed in water several minutes at 20 (3., whereby the yarn wasthoroughly wet out with consequent spontaneous elongation to the extentgiven in column 2 of the table below. The lengths of thread were thenpositively stretched to the length given in column 3. This amount ofstretching was not only suflicient to completely remove crimps, but toimpart substantial additional stretch to the thread itself. The threadswere then removed from the water, blotted to remove excess adheringliquor, and suspended freely in the air and allowed to completely dr ingently moving air currents. The figures given in column 4 indicate thefinal thread length.

iitinilt'ii Length after Length gth of dry crimpy Wetting ut n pp yi gthread alter thread water at 20 C. stretch drying Om. Cm, Cm Cm 10 i9. 625 6 10 19. 6 29 9 9 10 19. 6 32 3 4 10 19.6 30 3 10 i9. 6 35 10.3

It is to be noted that the thread undergoes practically completerecovery to its original length and that this result obtains, even withthe higher amounts of stretch given to the sample. In one case a 10 cm.length of original thread was wet out and stretched to 35 cm., but ondrying freely contracted with regain of crimp to within 10% of itsoriginal length.

In another set of tests, 10 cm. lengths of dry crimpy yarn werestretched in the dry state to varying amounts in addition to thatrequired to completely remove the crimps, but not sufficient to breakthe yarn or an substantial number of filaments thereof. In the case ofthe particular sample employed, a 10 cm. length was stretched to 19 cm.,which stretch was that required to just remove the crimps. While stillin the dry state, this sample was given an additional stretch of 3 cm.,whereby its length was increased to 22 cm. and the filaments all laysubstantially straight. This sample, while still being. maintained at 22cm., was wet with water and dried while maintaining its length at 22 cm.At this point, the filaments still lay substantially perfectly straightand parallel. While it might be expected that such a treatment haddestroyed the crimping power of the fiber, this is not the case, sincewhen this length of thread is again thoroughly wet by water and allowedto dry in a freely suspended state it will do so with marked contractionand development of crimps to the extent that its final dried length was12.4 cm. The filaments composing this yarn still presented a highlycrimpy appearance.

In order to still further exemplify the nature of the crimp which isinherent'in the fibers, the following experiment may be cited. Aconsiderable length of approximately 300 denier 40 filament crimpy yarnwas spun according to the process and after leaving the coagulating bathwas wound up on a perforated bobbin. The bobbin containing theunre'generated yarn was removed from the spinning machine and immersedin an acid regenerating bath. The yarn, while still on the same bobbin,was further. processed by washing free from acid, desulfurlng in hotsodium carbonate solution, followed by a thorough washing. Thereafterthe yarn, while still on the bobbin, was dried by means of heated air.It was found after drying that the filaments and the threads composedthereof lay on the bobbin in substantially straight form, having lostall the natural crimp as spun due to the fact that the yarn had beendried on a rigid support. The straightthreads were then wound onto asmall wooden spool under slight winding tension and thereafter thisspool was placed in an autoclave for one-half hour and heated in thepresence of lbs. steam pressure, following which the bobbin was removedfrom the autoclave. On unwinding the threads from the bobbin itwas foundthat the product possessed the appearance of ordinary straight filamentrayon, no indication of crimps being apparent. It might be supposed thatthis treatment had destroyed the tendency of the yarn to crimp, for notonly was the initial drying of the yarn on a rigid support carried outso as to remove all the crimps, but, in addition, the yarn inthis'straight form was further steamed under high pressure, whichtreatment has heretofore been used to set regenerated cellulosestructures in new and various shapes. However, after removing thethreads from the bobbin on which they had been steamed straight andcompletely wetting out these threads with water, followed by drying in afreely suspended condition, it was found that after drying they hadspontaneously assumed the usual highly crimpy form characteristic of theproducts and were substantially indistinguishable from yarns of theprocess which had not undergone such treatment.

The above examples serve to illustrate the inherent tendency of thefibers to regain their crimpy form after being given a variety oftreatments which would be expected to destroy the crimp. These tests arepurely exemplary and do not in any way limit the invention. The threadsor fibers may be submitted to still other conditions not included in theabove tests and still regain their crimpy form after wetting and freedrying. Wetting with water prior to drying in a free condition has beenmentioned and in this particular, it is to be understood that use may bemade of both cold and hot water, or even boiling water. Indeed, hot orboiling water will usually be more effective in the process of restoringthe fibers to their crimpy form than cold water. Many prior-art curly orkinky fibers, on the other hand, after treating with very hot or boilingwater lose or tend to lose their shape and tend to revert back to thestraight condition in -which they were spun.

The crimpy character of the product is such that it will, furthermore,persist after treatment by" various chemical agents such as soaps andother detergents, dilute acids, dilute alkalies and the like such as maybe commonly encountered in the dyeing and finishing industry.

The product, for instance, may be submitted to the action of causticsoda solution of concentrations up to several percent or even more, atroom temperatures or hot, without substantially affecting the crimpycharacter of the product when it is thereafter washed free from treatingliquor and finished. and dried as hereinbefore described.

The products of the invention are suitable for a wide variety of uses toobtain special effects in fabrics, which uses and effects have hithertobeen impossible to achieve with the inherently straight artificialfibers of the prior art. It may be used in the textile industry eitheras yarn composed of continuous crimpy filaments, or the fibers maybe cutup into'staple lengths and processed thereafter in this form, eitheralone or admixed with other fibers. It is often advantageous, however,in many cases and in the interest of economy to employ the product inthe form of continuous filament threads and achieve many novel fabriceffects. The product is suitable for both knitting and weaving a greatvariety of fabrics. Such fabrics will possess much greater body and loftthan when constructed from straight filament rayons or staple of theprior art. The product is particularly useful in the formation of pilefabrics in that the wildness of the filaments results in a uniquecharacter of the pile similar to that of a pile constructed from naturalwool. Due to the added covering power, bulk, and occluded air spaces infabrics constructed from .the fibers, they show an improved warmthcharacteristic over similar fabrics constructed from prior artartificial fibers. In general, fabrics so constructed will possess asomewhat worsted or woolly character and feel as compared to the thin,sleek, and rather cool character of fabrics constructed from prior artstraight filament yarns. Repeated observations carried out on fabricsconstructed from the products of the invention show that the crimpycharacter of the filaments carries over into the finished cloth and isto a large degree responsible for the special effects obtained therein.Furthermore, such fabrics may be submitted to wearing and repeatedwashing and drying without substantial loss of its uniquecharacteristics. This results from the permanent and inherent characterof the crimp imparted to the individual fiber by means of the invention.

It will be apparent from the above description of the process andproducts of the present invention that they are capable of greatextension and modification without departing from the nature and spiritof the invention and that one skilled in the art when taught by thisinvention may produce a great variety of fiber products showingcharacteristics and properties which have been hitherto unachieved inthe art of artificial fibers. It is, therefore, to be understood thatthe invention is not tobe limited except as set forth in the appendedclaims.

We claim:

1. The process of directly spinning crimpy filaments which comprisesextruding viscose, in the form of filaments, into a setting bath whichhas a sutliciently rapid coagulating action. relative to anyregenerating action thereof, to completely coagulate said filamentsprior to any substantial regeneration thereof, drawing said filamentsfrom the point where they are extruded into the bath, the velocity ofextrusion being at least four times the velocity of draw-off.

2. The process of directly spinning crimpy filaments which comprisesextruding viscose, in the form of filaments, into a setting bath havinga coagulating and regenerating action on said filaments, said bathhaving a sufficiently rapid coagulating action, relative to theregenerating action thereof, to completely coagulate said fila-' mentsprior to any substantial regeneration thereof, drawing said filamentsfrom the point where they are extruded into the bath, the velocity ofextrusion being at least four times the velocity of draw-off.

3. The process of directly spinning crimpy filaments which comprisesextruding viscose, in the form of filaments, into a setting bath havinga coagulating but no regenerating action on said filaments, drawing saidfilaments from the point where they are extruded into the bath, thevelocity of extrusion being at least four times the velocity ofdraw-off, and regenerating said filaments.

4. The process of directly spinning crimpy filaments which comprisesextruding viscose, in the form of filaments, into a setting bathcomprising an ammonium salt solution, which bath has a sufficientlyrapid coagulating action, relative to any regenerating action thereof,to completely coagulate said filaments prior to any substantialregeneration thereof, drawing said filaments from the point where theyare extruded into the bath, the velocity of extrusion being at leastfour times the velocity of draw-off.

5. The process of directly spinning crimpy filaments which comprisesextruding viscose, in the form of filaments, into a setting bathcomprising an ammonium sulfate solution, which bath has a suflicientlyrapid coagulating action, relative to any regenerating action thereof,to completely coagulate said filaments prior to any substantialregeneration thereof, drawing said filaments from the point where theyare extruded into the bath, the velocity of extrusion being at leastfour times the velocity of draw-01f.

6. The process of directly spinning crimpy filaments which comprisesextruding viscose, in the form of filaments, into a setting bathcomprising a solution of ammonium sulfate and sodium sulfate, which bathhas a sumciently rapid coagulating action, relative to any regeneratingaction thereof, to completely coagulate said filaments prior to anysubstantial regeneration thereof, drawing said filaments from the pointwhere they are extruded into the bath, the velocity of extrusion beingat least four times the velocity of draw-ofl.

7. The process of directly spinning crimpy filaments which comprisesextruding viscose, in the form of filaments, into a setting bathcomprising an acid, which bath has a sufilciently rapid coagulatingaction, relative to any regenerating action thereof, to completelycoagulate said filaments prior to any substantial regeneration thereof,drawing said filaments from the point where they are extruded into thebath, the velocity of extrusion being at least four times the velocityof draw-off.

8. The process of directly spinning crimpy filaments which comprisesextruding viscose, in the form of filaments, into a setting bath whichhas a sufllciently rapid coagulating action, relative to anyregenerating action thereof, to completely coagulate. said filamentsprior to any substantial regeneration thereof, drawing said filamentsfrom the point where they are extruded into the bath, the velocity ofextrusion being at least four times the velocity of draw-off, andstretching the crimpy filaments while in a wet state.

9. The process of directly spinning crimpy filaments which comprisesextruding viscose, in the form of filaments, into a setting bath havinga coagulating and regenerating action on said filaments, said bathhaving a sufiiciently rapid coagulating action, relative to theregenerating action thereof, to completely coagulate said filamentsprior to any substantial regeneration thereof, drawing said filamentsfrom the point where they are extruded into the bath, the velocity ofextrusion being at least four times the velocity of draw-off, andstretching the crimpy filaments while in a wet state.

10. The process of directly spinning crimpy filaments which comprisesextruding viscose, in the form of filaments, into a setting bath havinga coagulating but no regenerating action on said filaments, drawing saidfilaments from the point where they are extruded into the bath, thevelocity of extrusion being at least four times the velocity ofdraw-oil, regenerating said filaments and stretching the crimpyfilaments while in a wet state.

11. The process of directly spinning crimpy filaments which comprisesextruding viscose, in the form of filaments, into a setting bathcomprising an ammonium salt solution, which bath has a sufficientlyrapid coagulating action, relative to any regenerating action thereof,to completely coagulate said filaments prior to any substantialregeneration thereof, drawing said filaments from the point where theyare extruded into the bath, the velocity of extrusion being at leastfour times the velocity of draw-off, and stretching the crimpy filamentswhile in a wet state.

12. The process of directly spinning crimpy filaments which comprisesextruding viscose, in the form of filaments, into a setting bathcomprising an ammonium sulfate solution, which bath has a suflicientlyrapid coagulating action, relative to any regenerating action thereof,to completely coagulate said filaments prior to any substantialregeneration thereof, drawing said filaments from the point where theyare extruded into the bath, the velocity of extrusion being at leastfour times the velocity of draw-oil, and stretching the crimpy filamentswhile in a wet state.

13. A yarn, having a strength of at least .5 gram per denier, comprisingsubstantially noncrenulated regenerated cellulose filaments, themolecules of which have a substantially random distribution throughoutthe body thereof, said filaments having from 10 to 50 permanent crimpsper inch, said crimps lying in three dimensions, the crimps of saidfilaments being out of phase with each other.

14. A substantially non-crenulated regenerated cellulose filament,having a strength of at least 0.5 gram per denier, said filament havingpermanent crimps, said crimps lying, at random, in three dimensions.

15. A yarn, having a strength of at least 0.5 gram per denier,comprising substantially noncrenulated regenerated cellulose filaments,said filaments having permanent crimps, said crimps lying, at random, inthree dimensions.

16. A substantially non-crenulated regenerated cellulose filament,having a strength of at least 0.5 gram per denier, the molecules ofwhich have a. substantially random distribution throughout the bodythereof, said filament having permanent crimps, said crimps lying, atrandom, in three dimensions.

17. A yarn, having a. strength of at least 0.5 gram per denier,comprising substantially noncrenulated regenerated cellulose filaments,the

molecules of which have a. substantially random distribution throughoutthe body thereof, said filaments having permanent crimps, said crimpslying, at random, in three dimensions.

WILLIAM HALE CHARCH. WILLIAM FREDERICK UNDER-WOOD.

CERTIFICATE OF CORRECTION. Patent No. 2,2u9,7l+ ,July 22, 19in.

WILLIAM HALE CHARGE, ET AL.

It is hereby certified-that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,second column, line 1414., for the word "is" read --as--; page 5, secondcolumn, line 58, for "of" read --by--; page 1;, first column, line 5-6,for"depending read -dee'pen ?.ng; same page, second column, line 58, forthe word "centrifuging" read centr1mgally; page 6 second column, line10-11, for "threaded" read -created; and that the said Letters Patentshould be read with this correction therein that the same may conform tothe record of the case in the Patent Office. I

Signed and sealed this 7th day of October, A. D. 191 1;

Henry Van Arsdale, (Seal) Acting Commissioner of Patents.

